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Evaluating the role of created and natural wetlands in controlling nonpoint source pollution
Ecological Engineering, 1 (1992) xi-xv
xi
Elsevier Science Publishers B.V., Amsterdam
Editorial
Evaluating the role of created and natural wetlands in controlling nonpoint source pollution Richard K. Olson ManTech EnL,ironmental Technology, Inc., US EPA Enuironmental Research Laboratory, 200 S W 35th Street, Corvallis, OR 97333, USA
ABSTRACT Nonpoint source (NPS) pollution control and wetlands protection are two overlapping scientific and policy issues of the US Environmental Protection Agency. Created, restored, and natural wetlands can contribute significantly to watershed water quality but at the same time must be protected from degradation by NPS pollution. Effective use of wetlands in NPS control requires an integrated landscape approach including consideration of social, economic, and government policy issues as well as scientific knowledge. INTRODUCTION
This special issue of Ecological Engineering - The Journal o f Ecotechnology addresses two issues that are major environmental concerns and major policy issues for the US Environmental Protection Agency (EPA). (1) Nonpoint source (NPS) pollution contributes over 65% of the total pollution load to US inland surface waters (US EPA, 1989). Sources include urban stormwater, diffuse agricultural runoff from pastures and row crops, concentrated agricultural wastes from feedlots, runoff from building sites, forestry activities, and drainage from mining activities. (2) Over half of the wetlands in the southernmost 48 states of the USA have been lost during the past 200 years (Dahl, 1990), with some states losing more than 85% of their wetlands. Remaining wetlands are frequently degraded through physical alteration, hydrologic modification, and exposure to pollutants. Correspondence to: R.K. Olson, ManTech Environmental Technology, Inc., US EPA Environmental Research Laboratory, 200 SW 35th Street, Corvallis, OR 97333, USA. 0925-8574/92/$05.00 © 1992 - Elsevier Science Publishers B.V. All rights reserved
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R.K.OLSON
Addressing these two issues in an integrated manner makes sense in terms of both science and policy. Wetlands occupy depressions in the landscape and therefore are often recipients of waterborne pollutants. This exposure, coupled with the inherent ability of wetlands to sequester or transform many pollutants, gives them an important role in water quality improvement. This role can be consciously used in strategies to control NPS pollution by creating, restoring, or preserving wetlands in appropriate locations in the landscape. The other side of this issue is that wetlands can be degraded by NPS pollution. Preventing degradation of the full range of wetland functions may be at odds with maximizing their water quality functions. The policy linkages result from Sections of the Clean Water Act (CWA) (33 U.S.C. 1251 as amended) that give EPA responsibilities in wetland protection and NPS pollution control (US EPA, 1990). Under the CWA, most wetlands are considered to be "waters of the US" (Bastian et al., 1989) and are included within the CWA's objective to "restore and maintain the chemical, physical, and biological integrity of the Nation's waters". Section 404 of the CWA regulates the discharge of dredge and fill materials, and Sections 401 and 402 the discharge of waterborne pollutants into "waters of the US". Under Section 404, restoration or creation of wetlands may be required to mitigate wetland losses. Section 319 provides a mechanism for integrating Federal and State programs for controlling NPS pollution. States are required to perform, under EPA oversight and approval, assessments of the status of NPS pollution, and to develop management programs to control NPS pollution. Wetland protection, creation and restoration may be included in State 319 programs. Thus, the 404 program and related efforts may protect and restore wetlands and their water quality functions, to the benefit of NPS control programs. The NPS programs can protect wetlands from degradation by pollutants, while also identifying areas where wetland creation and protection will optimize wetland water quality functions. WORKSHOP In order to further define the scientific and policy linkages between NPS pollution and wetlands issues, the EPA Office of Research and Development and the Office of Wetlands, Oceans and Watersheds held a workshop on 10-11 June 1991, in Arlington, Virginia, USA. Within the overall theme of evaluating the role of created and natural wetlands in the control of rural NPS pollution, the workshop objectives were: (1) to review the state of knowledge; and
R O L E OF C R E A T E D AND N A T U R A L W E T L A N D S IN C O N T R O L L I N G NPS P O L L U T I O N
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(2) to identify research needs and approaches for developing guidelines for the inclusion of wetlands in NPS control strategies. The focus of the workshop was rural NPS pollution, exclusive of acid mine drainage. Urban stormwater and acid mine drainage are both important pollution sources for which wetlands can provide treatment. However, urban stormwater not only differs somewhat from rural NPS in its chemical constituents, but by definition occurs in a landscape from which many of the options for creation and use of wetlands have been lost. Acid mine drainage is very different chemically from most rural NPS pollution, and its treatment by wetlands requires consideration of a number of different issues. Restricting the workshop scope in this way still left for consideration a variety of nonpoint sources ranging in scale from local (e.g., swine farms) to watershed and regional, and a large number of scientific and policy questions concerning the use of wetlands to treat NPS pollution. Presentations during the first part of the workshop provided background on these issues, and papers corresponding to each presentation are included in this volume. WORKSHOP RESULTS Participants in the workshop included staff from the US EPA wetlands and NPS programs; representatives of the US Department of Agriculture, US Fish and Wildlife Service, and the US Army Corps of Engineers; and wetlands scientists from universities and consulting firms. This diversity of backgrounds and perspectives led to a corresponding diversity of ideas and opinions. A number of themes emerged, however, as unifying threads throughout the discussions and the papers in this volume. These include: • Natural wetlands should not be used as wastewater treatment systems. In most cases, natural wetlands are considered "waters of the US" and are entitled under the CWA to protection from degradation by NPS pollution. Natural wetlands do function within the watershed to improve water quality, and protection and restoration of wetlands to maintain or enhance water quality are acceptable practices. However, NPS pollutants should not be intentionally diverted to these wetlands, and wetlands receiving NPS loadings that will degrade the wetland should be protected by establishing upland buffer strips or other best management practices (BMPs). • Wetlands must be part of an integrated landscape approach to NPS control. Created, restored, and natural wetlands can contribute significantly to watershed water quality, but they must be sited correctly and not be overloaded. Wetlands cannot be expected to compensate for insufficient
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R K. OLSON
use of BMPs such as conservation tillage, grassed waterways, and exclusion of livestock from riparian areas. • The technical and scientific issues involved in defining the role of wetlands in NPS control will be relatively easy to resolve compared to the social and economic issues. Large-scale wetland creation or restoration efforts are expensive. Owners of key restoration sites may be unwilling to participate. Watersheds are a scientifically logical unit for NPS/wetlands programs, but rarely correspond with existing administrative units (e.g., farms or counties). • Knowledge of technical issues is uneven. Although more research is needed, design criteria for constructed wetland treatment systems have been fairly well worked out. Methods manuals for wetland creation and restoration are being developed by several Federal agencies, and much is known about the fate and effects of nutrients in wetlands. Topics with less sufficient information include water quality functions at the landscape scale. For example, improved models of sources and movement of NPS pollutants, and models of the role of wetlands in altering that movement are needed to guide siting decisions for wetland creation and restoration. The fate and effects of toxics (e.g., pesticides) in wetlands are not well known. Watershed-level demonstrations of the effects of wetland restoration and creation on water quality are lacking, but are needed both as a framework for research programs and as a technology transfer tool. CONCLUSIONS
The combination of wetlands and NPS pollution makes for complex scientific and policy issues. Technical issues must be addressed within the broader social and economic context if the research results are to contribute to improvements in water quality and wetlands protection. Mechanisms need to be developed to provide a strong link between science and policy development. Successful implementation of NPS control strategies involving wetlands will require participation of citizens, landowners, scientists, and government officials at every stage of the process. ACKNOWLEDGMENTS
This article has been prepared with funding from the US Environmental Protection Agency. It was prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, U.S.A. through contract No. 68-C8-0006 to ManTech Environmental Technology, Inc. It has been subjected to the Agency's peer and administrative review and approved for publication.
R O L E O F C R E A T E D AND N A T U R A L W E T L A N D S IN C O N T R O L L I N G NPS P O L L U T I O N
X'V
REFERENCES Bastian, R.K., P.E. Shanaghan and B.P. Thompson, 1989. Use of wetlands for municipal wastewater treatment and disposal - regulatory issues and EPA policies. In: D.A. Hammer (Ed.), Constructed Wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural. Lewis Publishers, Inc., Chelsea, MI, pp. 265-278. Dahl, T.E., 1990. Wetlands Losses in the United States: 1780's to 1980's. US Department of the Interior, Fish and Wildlife Service, Washington, DC, 21 pp. US Environmental Protection Agency, 1989. Focus on nonpoint source pollution. The Information Broker, Office of Water Regulations and Standards, Nonpoint Sources Control Branch, Washington, DC, November, 1989. US Environmental Protection Agency, 1990. National Guidance: Wetlands and Nonpoint Source Control Programs. Office of Water Regulations and Standards, and Office of Wetlands Protection, Washington, DC.
xi
Elsevier Science Publishers B.V., Amsterdam
Editorial
Evaluating the role of created and natural wetlands in controlling nonpoint source pollution Richard K. Olson ManTech EnL,ironmental Technology, Inc., US EPA Enuironmental Research Laboratory, 200 S W 35th Street, Corvallis, OR 97333, USA
ABSTRACT Nonpoint source (NPS) pollution control and wetlands protection are two overlapping scientific and policy issues of the US Environmental Protection Agency. Created, restored, and natural wetlands can contribute significantly to watershed water quality but at the same time must be protected from degradation by NPS pollution. Effective use of wetlands in NPS control requires an integrated landscape approach including consideration of social, economic, and government policy issues as well as scientific knowledge. INTRODUCTION
This special issue of Ecological Engineering - The Journal o f Ecotechnology addresses two issues that are major environmental concerns and major policy issues for the US Environmental Protection Agency (EPA). (1) Nonpoint source (NPS) pollution contributes over 65% of the total pollution load to US inland surface waters (US EPA, 1989). Sources include urban stormwater, diffuse agricultural runoff from pastures and row crops, concentrated agricultural wastes from feedlots, runoff from building sites, forestry activities, and drainage from mining activities. (2) Over half of the wetlands in the southernmost 48 states of the USA have been lost during the past 200 years (Dahl, 1990), with some states losing more than 85% of their wetlands. Remaining wetlands are frequently degraded through physical alteration, hydrologic modification, and exposure to pollutants. Correspondence to: R.K. Olson, ManTech Environmental Technology, Inc., US EPA Environmental Research Laboratory, 200 SW 35th Street, Corvallis, OR 97333, USA. 0925-8574/92/$05.00 © 1992 - Elsevier Science Publishers B.V. All rights reserved
xii
R.K.OLSON
Addressing these two issues in an integrated manner makes sense in terms of both science and policy. Wetlands occupy depressions in the landscape and therefore are often recipients of waterborne pollutants. This exposure, coupled with the inherent ability of wetlands to sequester or transform many pollutants, gives them an important role in water quality improvement. This role can be consciously used in strategies to control NPS pollution by creating, restoring, or preserving wetlands in appropriate locations in the landscape. The other side of this issue is that wetlands can be degraded by NPS pollution. Preventing degradation of the full range of wetland functions may be at odds with maximizing their water quality functions. The policy linkages result from Sections of the Clean Water Act (CWA) (33 U.S.C. 1251 as amended) that give EPA responsibilities in wetland protection and NPS pollution control (US EPA, 1990). Under the CWA, most wetlands are considered to be "waters of the US" (Bastian et al., 1989) and are included within the CWA's objective to "restore and maintain the chemical, physical, and biological integrity of the Nation's waters". Section 404 of the CWA regulates the discharge of dredge and fill materials, and Sections 401 and 402 the discharge of waterborne pollutants into "waters of the US". Under Section 404, restoration or creation of wetlands may be required to mitigate wetland losses. Section 319 provides a mechanism for integrating Federal and State programs for controlling NPS pollution. States are required to perform, under EPA oversight and approval, assessments of the status of NPS pollution, and to develop management programs to control NPS pollution. Wetland protection, creation and restoration may be included in State 319 programs. Thus, the 404 program and related efforts may protect and restore wetlands and their water quality functions, to the benefit of NPS control programs. The NPS programs can protect wetlands from degradation by pollutants, while also identifying areas where wetland creation and protection will optimize wetland water quality functions. WORKSHOP In order to further define the scientific and policy linkages between NPS pollution and wetlands issues, the EPA Office of Research and Development and the Office of Wetlands, Oceans and Watersheds held a workshop on 10-11 June 1991, in Arlington, Virginia, USA. Within the overall theme of evaluating the role of created and natural wetlands in the control of rural NPS pollution, the workshop objectives were: (1) to review the state of knowledge; and
R O L E OF C R E A T E D AND N A T U R A L W E T L A N D S IN C O N T R O L L I N G NPS P O L L U T I O N
xiii
(2) to identify research needs and approaches for developing guidelines for the inclusion of wetlands in NPS control strategies. The focus of the workshop was rural NPS pollution, exclusive of acid mine drainage. Urban stormwater and acid mine drainage are both important pollution sources for which wetlands can provide treatment. However, urban stormwater not only differs somewhat from rural NPS in its chemical constituents, but by definition occurs in a landscape from which many of the options for creation and use of wetlands have been lost. Acid mine drainage is very different chemically from most rural NPS pollution, and its treatment by wetlands requires consideration of a number of different issues. Restricting the workshop scope in this way still left for consideration a variety of nonpoint sources ranging in scale from local (e.g., swine farms) to watershed and regional, and a large number of scientific and policy questions concerning the use of wetlands to treat NPS pollution. Presentations during the first part of the workshop provided background on these issues, and papers corresponding to each presentation are included in this volume. WORKSHOP RESULTS Participants in the workshop included staff from the US EPA wetlands and NPS programs; representatives of the US Department of Agriculture, US Fish and Wildlife Service, and the US Army Corps of Engineers; and wetlands scientists from universities and consulting firms. This diversity of backgrounds and perspectives led to a corresponding diversity of ideas and opinions. A number of themes emerged, however, as unifying threads throughout the discussions and the papers in this volume. These include: • Natural wetlands should not be used as wastewater treatment systems. In most cases, natural wetlands are considered "waters of the US" and are entitled under the CWA to protection from degradation by NPS pollution. Natural wetlands do function within the watershed to improve water quality, and protection and restoration of wetlands to maintain or enhance water quality are acceptable practices. However, NPS pollutants should not be intentionally diverted to these wetlands, and wetlands receiving NPS loadings that will degrade the wetland should be protected by establishing upland buffer strips or other best management practices (BMPs). • Wetlands must be part of an integrated landscape approach to NPS control. Created, restored, and natural wetlands can contribute significantly to watershed water quality, but they must be sited correctly and not be overloaded. Wetlands cannot be expected to compensate for insufficient
xiv
R K. OLSON
use of BMPs such as conservation tillage, grassed waterways, and exclusion of livestock from riparian areas. • The technical and scientific issues involved in defining the role of wetlands in NPS control will be relatively easy to resolve compared to the social and economic issues. Large-scale wetland creation or restoration efforts are expensive. Owners of key restoration sites may be unwilling to participate. Watersheds are a scientifically logical unit for NPS/wetlands programs, but rarely correspond with existing administrative units (e.g., farms or counties). • Knowledge of technical issues is uneven. Although more research is needed, design criteria for constructed wetland treatment systems have been fairly well worked out. Methods manuals for wetland creation and restoration are being developed by several Federal agencies, and much is known about the fate and effects of nutrients in wetlands. Topics with less sufficient information include water quality functions at the landscape scale. For example, improved models of sources and movement of NPS pollutants, and models of the role of wetlands in altering that movement are needed to guide siting decisions for wetland creation and restoration. The fate and effects of toxics (e.g., pesticides) in wetlands are not well known. Watershed-level demonstrations of the effects of wetland restoration and creation on water quality are lacking, but are needed both as a framework for research programs and as a technology transfer tool. CONCLUSIONS
The combination of wetlands and NPS pollution makes for complex scientific and policy issues. Technical issues must be addressed within the broader social and economic context if the research results are to contribute to improvements in water quality and wetlands protection. Mechanisms need to be developed to provide a strong link between science and policy development. Successful implementation of NPS control strategies involving wetlands will require participation of citizens, landowners, scientists, and government officials at every stage of the process. ACKNOWLEDGMENTS
This article has been prepared with funding from the US Environmental Protection Agency. It was prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, U.S.A. through contract No. 68-C8-0006 to ManTech Environmental Technology, Inc. It has been subjected to the Agency's peer and administrative review and approved for publication.
R O L E O F C R E A T E D AND N A T U R A L W E T L A N D S IN C O N T R O L L I N G NPS P O L L U T I O N
X'V
REFERENCES Bastian, R.K., P.E. Shanaghan and B.P. Thompson, 1989. Use of wetlands for municipal wastewater treatment and disposal - regulatory issues and EPA policies. In: D.A. Hammer (Ed.), Constructed Wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural. Lewis Publishers, Inc., Chelsea, MI, pp. 265-278. Dahl, T.E., 1990. Wetlands Losses in the United States: 1780's to 1980's. US Department of the Interior, Fish and Wildlife Service, Washington, DC, 21 pp. US Environmental Protection Agency, 1989. Focus on nonpoint source pollution. The Information Broker, Office of Water Regulations and Standards, Nonpoint Sources Control Branch, Washington, DC, November, 1989. US Environmental Protection Agency, 1990. National Guidance: Wetlands and Nonpoint Source Control Programs. Office of Water Regulations and Standards, and Office of Wetlands Protection, Washington, DC.